CVE-2026-65655

Received Received - Intake

Temporal UI Server Missing Secure Cookie Attribute

Publication date: 2026-08-11

Last updated on: 2026-08-11

Assigner: Temporal Technologies Inc.

Description

When OAuth authentication is enabled and browser-facing TLS terminates at a reverse proxy that forwards the callback to Temporal UI Server over HTTP, affected versions derive authentication-cookie Secure attributes from the proxy-to-server connection. Temporal UI Server can therefore issue access-token cookies, and refresh-token cookies when provided by the identity provider, without Secure even though the browser completed login over HTTPS. A victim who visits attacker-controlled content while a credential remains live may expose that credential only if the attacker can also steer traffic for the UI hostname, prevent the browser's HTTPS connection from succeeding, serve the hostname over HTTP, and read a later same-site plaintext request. A malicious website alone cannot read the cookie, and passive observation of a successful TLS connection is insufficient. Effective HSTS, a blocking HTTPS-only warning, or TLS re-encryption between the proxy and Temporal UI Server prevents the demonstrated disclosure path. A recovered credential may be replayed within the victim's assigned permissions. Refresh-token replay additionally depends on the identity provider's issuance, expiry, rotation, and reuse-detection behavior.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-11

Last Modified

2026-08-11

Generated

2026-09-01

AI Q&A

2026-08-12

EPSS Evaluated

2026-08-30

NVD

CVE-2026-65655

EUVD

EUVD-2026-56924

Affected Vendors & Products

Vendor	Product	Version / Range
temporal	ui-server	2.53.1
temporal	ui-server	2.53.2

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-614	The Secure attribute for sensitive cookies in HTTPS sessions is not set.

Attack-Flow Graph

Executive Summary

This vulnerability involves OAuth authentication where browser-facing TLS terminates at a reverse proxy. The proxy forwards the callback to Temporal UI Server over HTTP, causing the server to incorrectly set authentication-cookie Secure attributes based on the proxy-to-server HTTP connection. This results in cookies being marked as non-Secure even when the browser login occurred over HTTPS.

Detection Guidance

Detecting this vulnerability requires checking if authentication cookies are improperly set without the Secure flag when OAuth is enabled and TLS terminates at a reverse proxy. Inspect network traffic for cookie headers during OAuth callbacks and verify cookie attributes in browser developer tools. Look for cookies marked as Secure only when the proxy-to-server connection uses HTTPS, which may indicate misconfiguration.

Impact Analysis

An attacker could potentially steal authentication cookies if they can manipulate traffic for the UI hostname, prevent HTTPS connections, or serve the site over HTTP. The stolen cookies could be replayed within the victim's permissions, allowing unauthorized access to the Temporal UI.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Compliance may be impacted if credentials are exposed, potentially resulting in data breaches and regulatory penalties.

Mitigation Strategies

Ensure TLS re-encryption between the reverse proxy and Temporal UI Server to prevent credential exposure.
Configure OAuth callback URLs to use HTTPS to enforce Secure cookie attributes.
Update to a patched version of Temporal UI Server where authentication cookies derive Secure attributes from the browser-facing callback URL scheme.
Implement HSTS policies to enforce HTTPS-only connections for the UI hostname.

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